CHEMISTRY [5 Mark Question Answer]

(a) Oxidation – The reaction in which oxygen is gained or hydrogen is lost, is called oxidation reaction. e.g. 2Cu+O2heat 2CuO
(b) Oxidising agent – The substance which give oxygen or substance which removes hydrogen
(c) Reduction – reduction is a process in which a substance removes oxygen or adds hydrogen. Examples: When copper oxide is heated with hydrogen, copper metal is formed along with the formation of water. In this reduction reaction, copper oxide loses oxygen atom to form copper.
(d) Reducing agent — a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that “donates” an electron to an electron recipient

(a) (i) Catalyst – A substance that alter the rate of a chemical reaction without itself undergoing any permanent chemical change is called a catalyst.
(ii) Inhibitor – an agent that slows or interferes with a chemical action. substance that reduces or suppresses the activity of another substance (such as an enzyme)
(iii) Promoter – the substances that enhances (increases) the activity of the catalyst.
(iv) Catalysis. – Catalysis is a term describing a process in which the rate and/or the outcome of the reaction is influenced by the presence of a substance (the catalyst) that is not consumed during the reaction and that is subsequently removed if it is not to constitute as an impurity in the final product.

(b) There are many catalysts that have important biological, commercial, and industrial applications. Enzymes are biological catalysts involved in a variety of vital processes in living organisms, including digestion. Other examples include the use of nickel to hydrogenate vegetable oils into margarine; the use of platinum in catalytic converters to covert carbon monoxide into carbon dioxide in cars

(a) Burning of candle - When a candle burns, the oxygen in the air reacts, formation of carbon dioxide takes place.
(b) Milk sours in hot and humid weather - Due to hot and humid weather lactose sugar present in the milk is converted into lactic acid which is a new substance formed
(c) Decomposition of water into hydrogen and Oxygen.- hydrogen and oxygen gases are produced from liquid water. The electrolysis of water causes a chemical change in which water molecules are split to form hydrogen and oxygen—two substances that are chemically different from water.
(d) Rusting of iron - When the iron is exposed to air and moisture, rust formation takes place. Rust is nothing but iron oxide; a new substance formed out of the reaction. The colour of the surface of the iron also changes. Hence, rusting of iron is a chemical change
(e) A frog breathes heavily - it is a chemical process as it utilizes this oxygen to break food to release energy